1. Field of the Invention
The present invention relates to a magnetic tape device in which a tape cassette can be surely injected.
2. Description of the Related Art
Conventionally, techniques of a magnetic tape device are disclosed in JP-A-4-310663 and the like. An example of such techniques will be described with reference to FIGS. 8 to 10. In this example, a pair of right and left guide plates 3a and 3b stand in parallel on a chassis 2 in a case 1. A plurality of guide rods 5 which protrude from the side faces of a tape cassette moving table 4 placed between the guide plates 3a and 3b are movably passed through substantially L-like guide holes 6 that are opened in the guide plates 3a and 3b, so that the moving table 4 can be moved forward and backward (a and b) between a cassette inserting position A and a cassette placing position B. Rocking levers 8 which are pivotally attached to the guide plates 3a and 3b via pivot shafts 7 so as to be swung forward and backward (c and d) are engaged with the front guide rods 5, respectively. A worm gear 11 which is rotated by a driving source (not shown) meshes with a worm gear 10 which is formed in an outer peripheral face of a center portion of a rotating cam 9 that is rotatably disposed on the rear face of the chassis 2. A bevel gear 12 formed in an upper outer peripheral face of the rotating cam 9 is interlockingly connected to a gear 13 formed in a basal end portion of the rocking lever 8 by a clutch gear mechanism 14. The reference numeral 15 denotes a top plate which extends between the guide plates 3a and 3b. 
Referring to FIG. 8, 17 denotes movable tape guide posts which pull out a magnetic tape t from a tape cassette T to wind the tape around a head cylinder 18, 19 denotes a full-track erase head, 20 denotes an audio erase head, 21 denotes an audio control head, 22 denotes stationary tape guide posts, 23 denotes a back tension posts, 24 denotes a capstan, and 25 denotes a pinch roller.
In the above-mentioned configuration, when a tape cassette T is injected into a tape cassette insertion port 1a of the case 1 under the state where the moving table 4 is on standby at the cassette inserting position A as indicated by the solid line in FIG. 10, the tape cassette T is inserted to the moving table 4 because the clutch of the gear mechanism 14 is disengaged, whereby the moving table 4 is slightly pushed-in in the direction of the backward motion b. In response to a detection signal from a detector (not shown) which detects the pushing-in, the clutch of the gear mechanism 14 is set to the engaged state by the driving source via the worm gear 11, the worm gear 10, and the rotating cam 9, and the rotating cam 9 and the rocking levers 8 are integrally interlockingly connected to each other via the gear mechanism 14. Thereafter, when the rocking levers 8 are swung backward (d) by the driving source, the moving table 4 is horizontally moved backward (b) along the guide holes 6, and then vertically lowered to be placed at the cassette placing position B (see the phantom line in FIG. 10). The magnetic tape t is then pulled out from the tape cassette T (see the phantom line in FIG. 8), and subjected to a process such as replay.
When an eject button (not shown) is pressed, the rocking levers 8 are swung forward (c) in response to an eject signal by the driving source via the gear mechanism 14 and the like. As a result, the moving table 4 at the cassette placing position B is vertically lifted along the guide holes 6, and then moved horizontally forward (a) to the cassette inserting position A, so that the tape cassette T is ejected (see the solid line in FIG. 10).
As shown in FIGS. 11A and 11B, a recessed groove 8a which is formed in a tip end portion of one of the rocking levers 8 is fitted onto the respective one of the guide rods 5, a press spring 16 is wound around a protruding portion 8b protruding from a center portion of the rocking lever 8, one end portion of the press spring 16 is engaged with an engaging piece 8c protruding from a front edge portion of the rocking lever 8, and the other end portion of the press spring 16 is engaged with the guide rod 5. Therefore, the pressing force P of the press spring 16 is applied to the moving table 4 via the guide rod 5 in the direction of the backward motion b, so that the moving table 4 placed at the cassette placing position B is prevented from being accidentally lifted by the pressing force P (see the phantom line in FIG. 10).
In the above configuration, under the state where the moving table 4 is on standby at the cassette inserting position A, the rocking lever 8 is held at the foremost position D as indicated by the solid line in FIG. 11A. When the tape cassette T is injected into the tape cassette insertion port 1a under this state, the tape cassette T is inserted to the moving table 4, whereby the moving table 4 is pushed-in in the direction of the backward motion b. In accordance with this pushing-in movement, the rocking lever 8 is swung backward (d), and the moving table 4 is passed through a predetermined pushing zone K to reach a detection position E (see the phantom line in FIGS. 11A and 11B). In response to the detection signal from the detector which detects the pushing-in, the operation is switched to an automatic pulling-in operation. The driving source is then activated to perform the above-mentioned operations, so that the moving table 4 is moved backward (b) to the cassette placing position B.
In the above configuration, when the tape cassette T is quickly injected, the pushing-in operation on the moving table 4 to which the tape cassette T is inserted is sometimes performed so insufficiently that the rocking lever 8 which has been once swung backward (d) is swung forward (c) by repulsion and the tape cassette T is pushed back to the tape cassette insertion port 1a. 